Another journalist was killed this weekend in the southern Mexican state of Veracruz. The body of Regina Martinez, a reporter for the political weekly magazine Proceso was found in the bathroom of her home in the city of Xalapa with signs of heavy blows and strangulation.

Martinez is the fifth journalist in Veracruz to be slain in the past 18 months, an ongoing battle between the Zetas drug cartel and members of the Chapo Guzman Sinaloa Cartel has contributed to a spiral of violence and corruption. Other journalists killed in the last year include Noel Lopez Olguin de Noticias de Acayucan, Miguel Angel Lopez, Misael Lopez Solana and Yolanda Ordaz of the newspaper Notiver. No one has been convicted or arrested in these cases.

Martinez was a Procesco reporter for more than a decade and she frequently wrote about drug trafficking.

The last story she filed for the magazine was about the arrest of nine police officers in the municipality of Tres Valle for alleged ties to organised crime. Martinez is the first Proceso reporter to be killed since the magazine was founded 36 years ago. People took to social networking sites to express their outrage over the murder and demand answers.

The latest murder will undoubtedly trigger a chilling effect, which will mean even less reporting on drug related violence. In parts of Mexico where organised crime has pushed journalists into silence, reporters and citizens have used social media networks to keep the public informed about violence and corruption.

This won’t happen in Veracruz, the state sent Twitter users Gilberto Martínez Vera and María de Jesús Bravo Pagola to prison on terrorism charges after they tweeted warnings about local drug gang violence. In a recent interview, the now released Martinez Vera described how his 21 days in prison last August destroyed his life. The mathematics professor now only tweets about religion out of fear of facing trouble once more. Both Martínez Vera and Bravo Pagola faced 30 years in prison if convicted on terrorism charges, they were released after an international outcry.

The second largest country in Latin America after Brazil, Mexico has the 14th largest economy in the world. The country has been shaken by the growth of powerful drug cartels that have wreaked havoc in Mexico’s regions.

The cartels have an insidious impact on civil society. A study by the Fundación de Periodismo de Investigación (MEPI) of 11 drug-affected provinces – almost half of Mexico’s state territories – found that newspapers report only three out of ten drug-related news stories, if not fewer. There is little official censorship, although press freedom at the state level is controlled by financial restraints, as the provincial press depend on state advertising.

I have been a journalist for three decades, in the 1980s I reported on Central America and its civil wars. In the 1990s I covered Colombia for US news outlets and since 1993, when I left daily journalism, I have focused on investigative journalism projects. I worked first for the New York based Committee to Protect Journalists and then moved to the Open Society Institute of West Africa, where I helped set up a media assistance project in Guinea Bissau. In 2007 I came to Mexico as a Knight international Fellow to train local newsrooms.

In January 2010 with the help of other journalists and editors I launched the Fundación de Periodismo de Investigación (MEPI) launched to promote investigations and work with journalists in the US, Mexico and Central America